Cancer is one of the most common causes of death in the world. About 10 million new cancer cases occur each year, and cancer is responsible for about 12% of the total cause of death, making cancer the third leading cause of death.
Among various kinds of cancers, particularly brain cancer is characterized in that it occurs regardless of age and the frequency of occurrence thereof in infants is higher than that of other cancers. Brain cancer collectively refers to primary brain cancer, which occurs in brain tissue and meninges surrounding the brain, and secondary brain cancer metastasized from cancer that occurred in the cranium or other areas of the body. This brain cancer differs in many respects from cancers that occur in other organs. Specifically, cancers that occur in the stomach, lung, breast and the like are limited to one or two kinds in each organ and generally have identical or similar characteristics. However, in the brain, very various kinds of cancers occur, including, for example, glioblastoma multiforme, malignant glioma, lymphoma, germinoma, metastatic tumors, and the like.
Among these brain cancers, glioma, particularly glioblastoma multiforme (GBM), is the most malignant and aggressive form of brain cancer, and thus is a very fetal disease that has a very poor prognosis and shows an average survival period of about 1 year or less after diagnosis. Since the boundary between brain cells and tumor cells is indistinct, it is almost impossible to completely remove GBM by surgery.
Despite an advance in the field of cancer treatment, current leading therapies include surgery, radiation and chemotherapy. Chemotherapeutic approaches are mainly used for treatment of, metastatic or particularly, aggressive cancer. Most of the cancer therapeutic agents that are currently used in clinical practice are cytotoxins. Cytotoxic agents work by damaging or killing cells that exhibit rapid growth.
Ideal cytotoxic agents would have specificity for cancer and tumor cells, while not affecting normal cells. Unfortunately, such ideal cytotoxic agents have not been found, and instead agents that target especially rapidly dividing cells (both tumor and normal) have been used. Accordingly, materials that are cytotoxic to cancer cells while exerting only mild effects on normal cells are highly desirable. In fact, recent many studies have been focused on the development of alternative anticancer agents that can particularly inhibit the growth of tumor cells.
Accordingly, the development of chemotherapeutic agents other than surgical therapy is urgently required, but effective therapeutic methods have not yet been developed, and thus the research and development thereof is required.